高盐废水分盐结晶工艺及其技术经济分析
Process introduction and techno-economic analysis on pure salt recovery crystallization for high salinity wastewater
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摘要: 为了在煤化工等行业的高盐废水零排放处理过程中,更好地选用和设计适宜的分盐结晶工艺,提高结晶盐的资源化效率,降低综合处理成本,首先介绍了高盐废水分盐结晶工艺各种典型技术路线,再结合特定煤化工案例,讨论了2种代表性的热法和膜法技术路线的分盐结晶工艺设计,并对其进行了定量的技术经济对比分析。结果表明,相较于热法分盐结晶工艺,纳滤-低温结晶膜法分盐工艺的投资虽然增加约30%,但其结晶盐产品的回收率提高37.8个百分点,在杂盐固废的处置成本为1 000元/t时,综合运行成本节省约30%,技术经济性上具有一定优势,且这一优势随杂盐固废处置成本的升高而增强。Abstract: It is of great importance to provide optimal pure salt recovery crystallization process designs and maximize recovery of pure salts at the lowest cost while achieving zero liquid discharge for the high salinity wastewater at coal chemical and other industries.In this paper,various typical pure salt recovery crystallization processes for high salinity wastewater were described and discussed.Exemplary pure salt recovery process designs were then provided and discussed with a high salinity coal chemical wastewater as the feed stream.Quantitative techno-economic analysis was further performed for the thermal and the membrane-based pure salt recovery crystallization processes.The results indicate that the membrane-based process shows 30% higher capital cost but saves 30% operation cost as a result of 37.8 higher percentage recovery rate of pure salts.It is concluded that the membrane-based process is a better solution in this case especially when the disposal cost of the mixed salt waste is high.